Thru-tubing stackable perforating gun system and method for use

Abstract

A stackable thru-tubing perforating gun system for use in perforating in a large diameter cased wellbore below a smaller diameter production tubing string. The system comprises a thru-tubing retrievable bridge plug for supporting a lower perforating gun section. The system further comprises at least one additional gun section stacked on top of the lower gun section. After firing, individual gun sections may be retrieved from the wellbore through the tubing string.

What is claimed is:  
     
       1. A method of perforating a casing of a well below a smaller diameter production tubing string, comprising the steps of: 
       conveying a through tubing retrievable bridge plug through the production tubing string into the casing;  
       setting the through tubing retrievable bridge plug into engagement with the casing;  
       lowering a first perforating gun section through the tubing;  
       landing the first perforating gun section onto the through tubing retrievable bridge plug;  
       lowering at least one additional perforating gun section through the production tubing;  
       landing the first at least one additional perforating gun section onto the first perforating gun section;  
       lowering a firing head on to a top perforating gun section;  
       firing said perforating gun sections and perforating the casing;  
       releasing said through tubing retrievable bridge plug from engagement with the casing after firing the perforating gun sections; and  
       retrieving the through tubing retrievable bridge plug from the casing through the production tubing.  
     
     
       2. The method of  claim 1  further comprising the step of retrieving at least one of the perforating gun sections from the casing through the production tubing. 
     
     
       3. A well perforating apparatus for perforating a casing of a well below a smaller diameter production tubing string comprising: 
       a cased wellbore;  
       a production tubing disposed in said wellbore;  
       a through-tubing retrievable bridge plug engagable with a portion of a well casing below said production tubing for providing a gun support within the casing;  
       a plurality of perforating gun sections, wherein one of said gun sections is a lower gun section being supported by the through-tubing retrievable bridge plug, and the remainder of said gun sections being supported by an adjacent gun section; and  
       a firing head for activating said gun sections.  
     
     
       4. The apparatus of  claim 3 , wherein the through-tubing retrievable bridge plug is adapted to release from engagement with the well casing after the lower gun section is fired. 
     
     
       5. The method of  claim 1 , further comprising centralizing at least one of said perforating gun sections in said casing by attaching at least one coil-spring actuated centralizer to said at least one perforating gun section. 
     
     
       6. The apparatus of  claim 3 , further comprising at least one coil-spring actuated centralizer for centralizing the plurality of gun sections in said casing.